A conventional sealing cover adopted for use on containers of varying openings, such as an example of a container 10 shown in FIG. 1 that has a round opening, mainly includes a cover 20 to cap a top rim 11 at the opening of the container 10. The cover 20 has an annular groove 23 at a location in contact with the top rim 11. A sealing pad 24 is provided in the groove 23. When the top rim 11 is wedged in the groove 23 it forms a close contact with the sealing pad 24.
The container 10 also has a plurality of jutting anchor portions 12 on an outer side close to the top rim 11. The cover 20 has the perimeter coupled with latch ledges 21 which can be rotated relative to the cover 20. Each of the latch ledges 21 has at least one aperture 22 corresponding to one anchor portion 12. When the cover 20 is mounted onto the opening of the container 10, the latch ledge 21 may be depressed towards the anchor portion 12 to allow the aperture 22 to be passed through by the anchor portion 12 to form a latched condition. Thus the cover 20 can tightly cap the opening of the container 10. By tightly compressing the sealing pad 24 in the groove 23 through the top rim 11 the internal space of the container 10 is isolated from the exterior to form a sealed condition.
However, after repetitive latching and rotating when in use for a period of time, the latch ledges 21 are prone to break or fracture at the joined locations. While increasing the thickness at the joined locations can reduce the risk of breaking or fracturing, to latch and disengage the latch ledges 21 when in use require a greater effort. It also is not operable single-handed. Moreover, the design of the anchor portions 12 makes the opening of the container 10 difficult to maintain a desired integrity. For instance, when the opening is circular, the apertures 22 of the latch ledges 21 have to be aligned accurately with the anchor portions 12 to form a tight coupling. It is not convenient in practice.
To solve the aforesaid problem, another type of cover 40 has been developed as shown in FIG. 2. A container 30 with a round opening also is used as an example to mate the cover 40. The container 30 has a smooth top rim 31 at the opening location. The cover 40 is located above the top rim 31. The cover 40 has an annular jutting portion 43 at a lower side and a lower surface around the annular jutting portion 43 to form a top coupling portion 41. The top coupling portion 41 has one spot extended outwards to form a moving flange 42. The annular jutting portion 43 has an outer diameter slightly smaller than the inner diameter of the opening of the container 30 and an annular groove 44 surrounding an outer wall thereof. A blade type sealing ring 45 is provided to be wedged in the groove 44 with a portion exposed outside. The sealing ring 45 has an air vent 46 in the center on a selected location.
When the cover 40 is caped on the top rim 31 of the container 30, the annular jutting portion 43 is squeezed in an inner side of the opening of the container 30. The air in the container 30 is discharged through the air vent 46 to allow the annular jutting portion 43 and the sealing ring 45 to be inserted by squeezing and compression until the top coupling portion 41 is in contact with the top rim 31. And the exposed sealing ring 45 is squeezed between the annular jutting portion 43 and the inner wall of the container 30 to isolate the internal space of the container 30 from the exterior to form a sealed condition. Through the moving flange 42 the cover 40 can be easily moved upwards and separated from the opening of the container 30.
While the blade type sealing ring 45 allows the opening of the container 30 to maintain the original shape, the air vent 46 for air discharging damages the sealing effect. Moreover, the sealing covers previously discussed provide only sealing function, but do not provide vacuuming function for the interior of the container.